1. Field of the Invention
The present invention relates to a light emitting diode device, and more particularly to a light emitting diode substrate with thin film light sensors integrated on the substrate.
2. Description of the Related Art
A liquid crystal display (LCD) device displays an image by using electro-optical properties of liquid crystals. Specifically, the LCD device includes an LCD panel for displaying an image through a pixel matrix and a driving circuit for driving the LCD panel. Since the LCD panel is a non-light-emitting device, the LCD device includes a backlight unit for supplying light to the LCD panel.
The backlight unit typically uses a lamp as a light source but recently, the trend has been shifting to using a light emitting diode (LED) having high luminance as a point light source. Since the point light source uses red (R), green (G) and blue (B) LEDs of three primary colors, a wide variety of colors can be produced by mixing the primary colors.
However, color uniformity is less than what is desirable when using the primary color LEDs. The reason for the low color uniformity is that the different-colored point light sources differ in luminous efficiency and aging characteristics. In order to prevent the color uniformity from decreasing, a luminance control circuit for controlling the luminance of the R, G and B LEDs or optical sensors for measuring luminous intensities is included in an LED driver. These additional components complicate the circuit configuration and raises manufacturing cost.